Basics in Understanding Flavour: Taste & Non-Volatiles
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April 13, 2024Flavour and how we perceive it is a vastly complex subject, one that encapsulates all the senses in one way or another.
We covered touch only a few issues ago, when we discussed the importance of the somatosensory system on how we perceive flavour through touch.
Before we start this journey, I would like to point out that whenever we talk about flavour, we almost always refer to it as a perception, unless we are talking about measurable and detectable flavour compounds. Humans are vastly complex beings, and the perceived final flavour of an object is subjective to the individual, with all of us having our own life experiences, physiology and sensory thresholds which will all affect the final enjoyment (and thus flavour) of the product we are consuming.
Taste and smell make up roughly 90% of the total sum of what flavour is (although the actual figures would be hard to quantify), but without these senses working in harmony we would never understand what flavour truly is. Consider when your nose is blocked, the flavour of the food changes, this is because light volatile compounds cannot attach themselves to your nasal receptors, but heavy non-volatiles can attach themselves to your taste receptors on your tongue, giving us taste but no flavour. On the opposite side of the spectrum, without our tongue, food would just be aroma and nothing else.
In essence, taste is what we “feel” on our tongues or to be more accurate, a reaction where a receptor on your tongue binds to its corresponding heavy chemical compound and sends messages to the brain telling us that there is one or more of the five tastes that has reacted with a receptor. These five tastes will almost always enter the mouth through a non-volatile flavour compound, i.e. a chemical that is too heavy to be smelled. Salt (sodium chloride) is a fantastic example, in most cases odourless, it reacts brilliantly with our sodium chloride receptors, giving us a salty taste. Although it's more complicated than that, but I’ll try to keep it short.
Our tongue is littered with thousands of taste buds, all at random, dispersed around the tongue. So that tongue map you learnt at school is basically a lie, with a single exception, super-tasters. Each taste bud is responsible for picking up one of the five tastes; sweet, sour, salty, bitter and umami. Each taste bud then contains hundreds of receptors, whose job is to pick out one specific type of non-volatile compound.
Take our sour taste bud, it detects acids present in food and beverages, but each acid receptor on our taste bud can only pick up one type of acid, say acetic acid in vinegar or malic acid in apples. This is why each acid has such a different taste, and why as Chefs we need to have a vast array of ingredients rich in non-volatiles. The more acids present, even in the smallest amounts, the more amusing it is to the brain. Take lemons, their juice contains citric and ascorbic acid, making it far more appealing to us then just pure citric acid, and thus having a better overall taste.
One of the (many) reasons chocolate is appealing to us is the diversity of non-volatiles in it. Ascorbic, malic, lactic, glutamic, and acetic acids are all present in it, along with a variety of other non-volatiles. Obviously, chocolate is rich in volatiles which also helps, but we will cover that in another issue.
All taste receptors work the same way, they just bind to different compounds. Salt receptors will pick up the presence of sodium chloride (salt) and alkaline salts like sodium carbonate (bicarbonate of soda, used in baking) and potassium carbonate (lye used to make ramen noodles), although these salts can leave a metallic taste in the mouth. Sweet taste receptors pick up sugars, like sucrose (table sugar), maltose (malt powder and honey), fructose (all fruit and some grains) and so on.
Sweet receptors can also pick up sugar-like molecules like steviosides found naturally in stevia leaf or aspartame, a man-made sweetener. Bitter receptors bind to heavy bitter compounds, some toxic like theobromine and caffeine in chocolate and coffee respectively, and some not. Most plants, especially leafy greens, will create bitter compounds as a deterrent to pests.
The bitter receptors can also pick up some heavier volatile compounds, namely phenols. Umami, the final and most recently discovered taste (discovered by a Japanese scientist in the 1910’s) binds to glutamates and nucleotides, both of which can be found naturally in several foods, namely fungi, animal proteins, fermented foods and so on. “Flavour enhancers” like monosodium glutamate (MSG), are simply salt forms of these compounds and are usually extracted through natural means.
How does all this relate to better results in the food and beverage industry?
Here are some tips and facts.
Infants have more sour receptors and enjoy acidity more than adults as sourness usually indicates the presence of vitamins and thus plays an important evolutionary role. Children tend to have more bitter receptors, this is a defence mechanism so they don’t eat toxic foods as most toxins are bitter, try foods with less bitter compounds. Adults have a particular fondness for bitterness, with our brain considering it to be exciting, sometimes, in limited amounts.
“Super tasters” are people with large clusters of one specific taste bud, although it's usually the bitter taste bud, these individuals are more sensitive to it, making that taste more pronounced. Some of us are missing receptors, that means that we might not pick up a specific taste, again this is more common with bitter receptors where some compounds can only be picked up by one in five people.
Some receptors take priority, meaning that you can mask or mellow certain tastes. Salt tends to mask bitterness while sweet tends to mellow out acidity, while incorporating all five tastes in a dish will arouse the mind and result in the food having a better flavour.
Test and measure for more consistency. One of the exercises I do with my students is to show how we can gain more consistency through simple measurements, pH metres to test acidity, Brix refractometer to measure for sweetness, and salinity metre to test salt content. Remember each ingredient, although identical in theory, are going to have different amounts of compounds.
Taste is one of the simpler parts of the entire flavour equation, but it plays an important and pivotal role in the entire dining experience, and understanding these systems can give us the knowledge we need to really elevate gastronomy. We are all built differently, and when someone says something is too sweet or too bitter, remember they’re not tasting what you are.
Stay tuned for Part 2 where in Issue 16 Keith will be looking at aroma and smell and how they affect our perceived flavour.
Keith Abela
Keith Abela is a forager, product developer and local food consultant. Who spends all of his time researching the delicious, rare and unique ingredients Maltese nature has to offer. He has a particular interest in multisensory flavour perception and all things fungus.
Click here to see Horeca Issue 15 online
Taste and smell make up roughly 90% of the total sum of what flavour is (although the actual figures would be hard to quantify), but without these senses working in harmony we would never understand what flavour truly is. Consider when your nose is blocked, the flavour of the food changes, this is because light volatile compounds cannot attach themselves to your nasal receptors, but heavy non-volatiles can attach themselves to your taste receptors on your tongue, giving us taste but no flavour. On the opposite side of the spectrum, without our tongue, food would just be aroma and nothing else.
In essence, taste is what we “feel” on our tongues or to be more accurate, a reaction where a receptor on your tongue binds to its corresponding heavy chemical compound and sends messages to the brain telling us that there is one or more of the five tastes that has reacted with a receptor. These five tastes will almost always enter the mouth through a non-volatile flavour compound, i.e. a chemical that is too heavy to be smelled. Salt (sodium chloride) is a fantastic example, in most cases odourless, it reacts brilliantly with our sodium chloride receptors, giving us a salty taste. Although it's more complicated than that, but I’ll try to keep it short.
Our tongue is littered with thousands of taste buds, all at random, dispersed around the tongue. So that tongue map you learnt at school is basically a lie, with a single exception, super-tasters. Each taste bud is responsible for picking up one of the five tastes; sweet, sour, salty, bitter and umami. Each taste bud then contains hundreds of receptors, whose job is to pick out one specific type of non-volatile compound.
Take our sour taste bud, it detects acids present in food and beverages, but each acid receptor on our taste bud can only pick up one type of acid, say acetic acid in vinegar or malic acid in apples. This is why each acid has such a different taste, and why as Chefs we need to have a vast array of ingredients rich in non-volatiles. The more acids present, even in the smallest amounts, the more amusing it is to the brain. Take lemons, their juice contains citric and ascorbic acid, making it far more appealing to us then just pure citric acid, and thus having a better overall taste.
One of the (many) reasons chocolate is appealing to us is the diversity of non-volatiles in it. Ascorbic, malic, lactic, glutamic, and acetic acids are all present in it, along with a variety of other non-volatiles. Obviously, chocolate is rich in volatiles which also helps, but we will cover that in another issue.
All taste receptors work the same way, they just bind to different compounds. Salt receptors will pick up the presence of sodium chloride (salt) and alkaline salts like sodium carbonate (bicarbonate of soda, used in baking) and potassium carbonate (lye used to make ramen noodles), although these salts can leave a metallic taste in the mouth. Sweet taste receptors pick up sugars, like sucrose (table sugar), maltose (malt powder and honey), fructose (all fruit and some grains) and so on.
Sweet receptors can also pick up sugar-like molecules like steviosides found naturally in stevia leaf or aspartame, a man-made sweetener. Bitter receptors bind to heavy bitter compounds, some toxic like theobromine and caffeine in chocolate and coffee respectively, and some not. Most plants, especially leafy greens, will create bitter compounds as a deterrent to pests.
The bitter receptors can also pick up some heavier volatile compounds, namely phenols. Umami, the final and most recently discovered taste (discovered by a Japanese scientist in the 1910’s) binds to glutamates and nucleotides, both of which can be found naturally in several foods, namely fungi, animal proteins, fermented foods and so on. “Flavour enhancers” like monosodium glutamate (MSG), are simply salt forms of these compounds and are usually extracted through natural means.
How does all this relate to better results in the food and beverage industry?
Here are some tips and facts.
Infants have more sour receptors and enjoy acidity more than adults as sourness usually indicates the presence of vitamins and thus plays an important evolutionary role. Children tend to have more bitter receptors, this is a defence mechanism so they don’t eat toxic foods as most toxins are bitter, try foods with less bitter compounds. Adults have a particular fondness for bitterness, with our brain considering it to be exciting, sometimes, in limited amounts.
“Super tasters” are people with large clusters of one specific taste bud, although it's usually the bitter taste bud, these individuals are more sensitive to it, making that taste more pronounced. Some of us are missing receptors, that means that we might not pick up a specific taste, again this is more common with bitter receptors where some compounds can only be picked up by one in five people.
Some receptors take priority, meaning that you can mask or mellow certain tastes. Salt tends to mask bitterness while sweet tends to mellow out acidity, while incorporating all five tastes in a dish will arouse the mind and result in the food having a better flavour.
Test and measure for more consistency. One of the exercises I do with my students is to show how we can gain more consistency through simple measurements, pH metres to test acidity, Brix refractometer to measure for sweetness, and salinity metre to test salt content. Remember each ingredient, although identical in theory, are going to have different amounts of compounds.
Taste is one of the simpler parts of the entire flavour equation, but it plays an important and pivotal role in the entire dining experience, and understanding these systems can give us the knowledge we need to really elevate gastronomy. We are all built differently, and when someone says something is too sweet or too bitter, remember they’re not tasting what you are.
Stay tuned for Part 2 where in Issue 16 Keith will be looking at aroma and smell and how they affect our perceived flavour.
Keith Abela
Keith Abela is a forager, product developer and local food consultant. Who spends all of his time researching the delicious, rare and unique ingredients Maltese nature has to offer. He has a particular interest in multisensory flavour perception and all things fungus.
Click here to see Horeca Issue 15 online
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